Technical Field
Embodiments of the subject matter disclosed herein generally relate to an apparatus and method for efficiently deploying a downhole tool.
Discussion of the Background
A downhole tool may be a device used to conduct seismic surveys in downhole environments, such as, for example, inside of wells used for oil and gas extraction. Downhole tools may contain sensors, such as, for example, geophones, temperature sensors, pressure sensors, accelerometers, optical sensors, etc. In order to function properly, a downhole tool that has been lowered into a well may need to be anchored in place with the tool pressed up against the wall of the well. Several tools may be connected together, top to bottom, along with other survey equipment, using a cable, and lowered into a well.
FIG. 1 depicts an exemplary downhole tool 101, which in this case is a seismic tool. Seismic tool 101 may include a main housing 102, upper cable head 103, lower cable head 104, and anchoring arm 106. A logging cable 105 may be connected to the upper cable head 103 at the top and the lower cable head 104 at the bottom of the seismic tool 101. Main housing 102 may be a housing of any suitable shape and made of any suitable material for enclosing any equipment, such as, for example, sensors, motors, and other mechanical, electric, and electronic components, within the seismic tool 101. Upper cable head 103 and lower cable head 104 may enclose seismic tool 101 on the top and bottom ends, respectively, and may be made of a similar material to the main housing 102 or any appropriate material. Anchoring arm 106 may be made of any suitable material in any suitable shape for allowing seismic tool 101 to be lowered into a well when anchoring arm 106 is in a closed position, and to anchor seismic tool 101 against the wall of the well when anchoring arm 106 is in an open position. For example, anchoring arm 106 may be made of metal in a curved scoop shape. Anchoring arm 106 may be attached to the main housing 102 in any suitable manner to allow anchoring arm 106 to switch between closed and open positions. FIG. 2 shows another downhole tool 201, which is similar to downhole tool 101, but does not have an anchoring arm. For example, if the downhole tool measures the pressure and/or temperature inside the well, the tool does not have to be in contact with the casing or tubing of the well.
Logging cable 105 may connect the seismic tool 101 to other devices, such as, for example, other seismic tools, telemetry devices, or electronic devices that allow the seismic tool 101 to transmit data to a computer. For example, seismic tool 101 may be deployed in a string of similar seismic tools, and may be connected to other seismic tools 101 above and below through the logging cable 105 as illustrated in FIG. 3. FIG. 3 shows a system 300 that includes multiple tools 306 to 310 deployed in a well 302. Tools 306 to 310 may be lowered into the well 302 from the surface by main logging cable 304. Logging cable 105 may connect tools 306 to 310 to each other, a telemetry unit 305 and an end unit 320. Main logging cable 304 may connect an electronic device 322, which is part of end unit 320, to telemetry unit 305, and may be used to control the descent and ascent of all of the seismic survey equipment within the well 302. In one application, main logging cable 304 may be different from logging cable 105. Electronic device 322 may serve as an interface between the tools 306 to 310 and a computer 324 through a link 326. Computer 324 may be any suitable computing device for gathering data from and sending commands to tools 306 to 310, and the end unit 322. Telemetry unit 305 may collect data from sensors in tools 306-310 for transmission to the electronic device 322 and computer 324.
When tools 306-310 are deployed inside the well 302, a large tension may develop within logging cable 105, as the number N of the tools may vary between 20 and 200 and the weight of each unit may be in the tens of kilograms. Thus, a total weight of the tools when deployed in the well and hanging from main logging cable 304 can reach several tons. Further complicating the deployment process is the necessity to use a crane for lifting each tool from the ground and deploying it in the well with all the other deployed modules hanging from the current module. This process is schematically illustrated in FIG. 4 in which plural tools 406-410 are shown, some of them (409, 410) already deployed in well 402, and some of them (406, 407) waiting to be deployed.
A crane 430 (partially shown) is connected with cables 432 to corresponding brackets 434 of a deployment device 436 (called “bottle” in the art). Deployment device 436 is a cylinder configured to house tool 408, that is connected through logging cable 105 to a next tool 407 and also to tools 409 and 410, already deployed in the well. Thus, a large force (exerted by all the tools 409 and 410 already deployed inside the well) is applied to current tool 408, which is waiting its turn for being deployed inside the well. Current tool 408 is connected with another logging cable 105 to a next tool 407, which lies on the ground with other tools 406. A second deployment device 438 is used for housing the next tool 407. Note that existing deployment devices are configured to receive the entire tool, except a top portion. Current tool 408, together with first deployment device 436, are supported by a rig-up plate 440, which sits on ground 442 on top of well 402. Rig-up plate 440 has a slit (not shown) that permits logging cable 105 to be removed when required. Both deployment devices 436 and 438 also have corresponding slits extending all the way along their length so that they can be removed from logging cables 105. After current tool 408 and first deployment device 436 are placed on rig-up plate 440, crane's cables 432 are removed from first deployment device 436 and are now attached to the second deployment device 438. After next tool 407 is secured to second deployment device 438, crane 430 raises second deployment device 438 together with next tool 407 until current tool 408 is raised from its first deployment device 436. As this stage, the first deployment device 436 is removed from logging cable 105 and the next tool 407 is lowered with its second deployment device 438 on top of the rig-up plate 440, which is placed on top of the well after current tool 408 has entered the well. Note that this operation is necessary as an opening in the rig-up plate is smaller in diameter than an external diameter of the tool. Next, the freed first deployment device 436 is used to house the next tool 406 and the process continues in this way until all the tools are deployed inside the well.
Prior to being deployed, the tools are connected to each other, both mechanically and electrically along a bidirectional link. Thus, one can communicate with the tools along the bidirectional link. Therefore, prior to deploying the tools into the well, they are connected to each other as illustrated in FIG. 4 and tested. However, it is customary to unchain the tools after this test and chain them again while being deployed in the well.
The operation of deploying the tools into the well is of particular complexity as discussed above with regard to FIG. 4. This operation brings up safety issues. Indeed, the mechanical tension induced by the weight of the tools already disposed into the well could reach several tons. As the tools are laid onto the floor prior to being deployed, there is a risk that the tools may get carried by the tension of the logging cable 105 and hurt the operator. Therefore, there is a need to control the tension in the logging cable and deploy tools into the well with no tension and no risk regarding human safety.
There are further drawbacks with the method described above. There is a need for two deployment devices to actually deploy one tool. Also, the deployment process is slow, which increase the cost of the operation. Further, as the deployment tools have to be constantly raised and lowered under high tension, it increases the safety risks associated with the equipment manipulation. In particular, when removing the deployment device, it happens sometimes that it falls down on the floor, potentially injuring the equipment's operator.
Thus, there is a need for an apparatus and method for deploying in a faster and safer way a chain of downhole tools.